35 



species ought to be admitted into its Flora, and what species 

 excluded. And as new plants come in, so do old plants from 

 time to time die out. This may arise from the failing of some of 

 those conditions necessary to secure their continuance in a 

 healthy state to which we before alluded. But it is oftener due 

 to causes more constraining than these, such as drainage, 

 enclosure, and the clearing of forests. It would be difficult to 

 estimate what have been the combined eifects of these operations in 

 diminishing the number of our old original British plants, since 

 civilisation first made a start in these islands. We may imagine 

 how much richer a field must have been open to the researches of 

 the botanist in our own neighbourhood, if we go back in thought 

 to the days of the Komans, when the slopes of the hills round 

 Bath were all thickly clothed as they probably were, and as they 

 still are in places, Avith trees and brush-wood ; and the valleys 

 still unreclaimed for arable pasture. Nor is there a doubt that 

 riot here only but in most parts of the country many species were 

 formerly plentiful, which are now extremely rare, whilst a 

 considerable number have been altogether extirpated. And 

 there is still another cause, we regret to say, tending to bring 

 about this extirpation — the greediness of collectors and cultivators 

 of rare plants, who, not content with one or two specimens for 

 their herbarium or garden, will sometimes well-nigh eradicate 

 all they find. 



Perhaps it is not too much to say that few years pass without 

 one or more species, in different localities, succumbing to their 

 fate from some of the above causes. And the straitened circum- 

 stances under which others are placed, though they may continue 

 to exist, will go towards explaining why certain plants are 

 found at the present day cooped up within such extremely 

 narroAv limits. The areas over which they may have formerly 

 ranged have been more and more contracted until they are at 

 last driven into a corner, where alone they can any longer hold 

 their ground. 



